Human Rated Atlas V for Bigelow Space Station details emerge

January 31, 2007 by Braddock Gaskill

United Launch Alliance (ULA) is continuing to study and promote the use of the Atlas V for commercial passenger transportation, including space tourism and transportation to the proposed Bigelow Aerospace orbital station.

A partnership between Lockheed (now ULA) and Bigelow was announced in September to study in detail the feasibility of use of the Atlas V to bring space tourists and other paying passengers to the Bigelow station. Documentation recently obtained by NASASpaceFlight provides additional details covering Atlas V orbital and trajectory considerations for safe launch abort contingencies for manned flights.

Several presentations relating to Atlas HR, Commercial and Space Tourism, Atlas X and the Black Zones presentation are available to download on L2.

ULA has recommended to Bigelow that it place their space station in a 264nmi circular repeating ground track orbit at 41 degrees inclination that would provide daily launch opportunities.

The repeating ground track would bring the station over the same locations on the Earth every day, and would provide crew landing opportunities four times per day at the Utah Test Range or Edwards AFB with minimal cross-range requirement.

The obtained document indicates that the Atlas V 401 can launch manned payloads of up to 20,300 lbs without any ‘black zones’. An Atlas 402 with two Centaur engines, can easily close Black Zones with even larger payloads using standard ‘Mission Planners Guide’ rules. A ‘black zone’ is a time period during launch when the crew would be unable to safely escape or abort in the event of a failure of the launch vehicle.

To avoid black zones, the rocket’s trajectory and flight path must be optimized. The flight path must avoid geographic locations where an abort would send the capsule into hostile terrain, such as the Alps or North Atlantic. The ascent trajectory must also be shaped to avoid subjecting the crew to fatal accelerations during an abort – in the case of the Atlas 401 this translates to a depressed ascent with a flatter trajectory.

The 41 degree orbital inclination helps to avoid the potential for aborts into the North Atlantic or the Swiss Alps, which can be a significant concern for higher inclination orbits.

NASA’s Exploration Systems Architecture Study (ESAS) last year cited the inability of the Atlas V in its heavier configurations to close ‘black zones’ while meeting CEV requirements as one concern in their elimination of EELV’s for human flight in favor of the Ares I. However, the CEV capsule mass requirements for the ESAS study were more than double the capsule mass that ULA and Bigelow are studying.

The smaller Bigelow passenger vehicle can be launched on the smaller Atlas V 401 or 402 configurations, instead of the three-core wide Atlas Heavy, or solid-boosted Atlas 55X required by the large ESAS CEV. The smaller mass and configuration provides enough performance margin to shape the flight trajectory to eliminate all black zones.

Also, because the Atlas V common core structure was designed for the higher stresses of the larger configurations, the 401/402 configurations can easily meet the structural 1.4 factor of safety margins for human space flight laid out by NASA without modification.

Indeed, the ‘Apollo on Steroids’ CEV mass requirements for the ESAS study were more than twice the mass than for the earlier Orbital Space Plane (OSP) and early CEV capsule concepts. The Orbital Space Plane was the CEV’s immediate predecessor, and had been studied in-depth for NASA by various contractors, including Lockheed Martin.

ULA’s current work to demonstrate that the Atlas V can be safe for human flight heavily leverages its earlier OSP project investigations. The announcement of the Bigelow and ULA (then Lockheed) partnership was accompanied by a paper by Lockheed published at the AIAA conference Space 2006 in September entitled ‘Atlas V for Commercial Space Transportation‘ which outlined many of the considerations for human-rating the Atlas V.

Bigelow Aerospace has developed and tested an inflatable space station module in its efforts to establish a commercial space hotel and laboratory in low earth orbit. The company successfully launched and tested a small prototype station module, ‘Genesis I’, on a Russian Dnepr launcher early last year. Bigelow intends to launch the ‘Genesis II’ prototype from ISC Kosmotras in early April.

The announcement in September that Bigelow and Lockheed (now ULA) were jointly studying the use of the Atlas V represented a fundamental shift for Bigelow Aerospace. The company seemed content to allow the commercial passenger market to develop independently, and has even allocated a future launch from SpaceX on the delayed Falcon 9.

The active partnership with ULA indicates that Bigelow desires an accelerated schedule and is no longer as willing to passively wait for a suitable launch vehicle to become available.